Field of the Invention
The present invention relates to a method, a kit, and an apparatus for evaluating the presence or absence of an ischemic heart disease, for example, stable angina or acute myocardial infarction, and/or the seriousness thereof.
Background Art
The number of patients with heart diseases such as angina pectoris or myocardial infarction is rapidly increasing along with the westernization of diet or the aging society. Such heart diseases are principally caused by rupture of unstable plaques formed in arterial vessels by arteriosclerosis, rapid thrombus formation, and resultingly evoked myocardial ischemia (ischemic heart disease). For the in vitro diagnosis of these heart diseases, traditional risk factors (age, sex, obesity, hyperlipidemia, hypertension, hyperglycemia, and smoking) as well as testing methods using inflammation, vascular endothelial disorder, or a thrombus formation-related factor as an index have been discussed in a large number of epidemiologic studies. Among others, C-reactive protein (CRP) has been studied most frequently as a biomarker and has also been evaluated by large clinical trials. At this time, however, the CRP level alone cannot serve as an index for the risk of an ischemic heart disease. Thus, the challenge to ischemic heart diseases has been to develop a convenient testing method with excellence in quantitative performance and reproducibility using a novel biomarker (Wang X. and Connolly T. M., Advances in Clinical Chemistry, Vol. 50, p. 1-22, 2010).
Previous reports disclosed a method for testing the presence or absence of arteriosclerosis or determining the progression stages, comprising: identifying, by proteome analysis, a protein group whose expression varies with the progression of arteriosclerosis; recording this variation as an expression profile database; and checking variation in protein expression in a sample against the database (JP Patent Publication (Kokai) Nos. 2011-232218 A (2011) and 2012-107989 A (2012)). JP Patent Publication (Kokai) No. 2011-232218 A (2011) has revealed by analysis using mouse models of arteriosclerosis that the expression levels of a group of proteins including complement factor D correlate with the seriousness of arteriosclerotic ischemic heart disease. JP Patent Publication (Kokai) No. 2012-107989 A (2012) has revealed that, since the expression levels of a group of proteins including complement factor H vary at an arteriosclerotic plaque site, the expression levels of these proteins at the arteriosclerotic plaque site (tissue slice) can be assayed to thereby evaluate the seriousness of arteriosclerotic ischemic heart disease.
The complement factor H or the complement factor D is a protein that is involved in immune or inflammatory response and included in a “the complement system” known as one of biological control mechanisms. The complement system is constituted, as shown in FIG. 6, by a group of 20 or more types of proteins (complement factors) present in blood. Complement receptors or complement regulatory membrane factors are found on the surface of blood cells contained in blood or vascular endothelial cells. Upon invasion of pathogens or inflammatory stimulation, these proteins cause a chain reaction, thereby activating complements (or the complement system). Meanwhile, the complement factors as well as regulatory factors perform strict regulation in order to prevent unfavorable “activation” from being out of control. Reportedly, patients genetically deficient in mannose-binding lectin, a complement factor, have an advanced stage of arteriosclerosis and are often affected by heart diseases (Madsen H. O., Videm V., Svejgaard A., Svennevig J. L., and Garred P., Lancet, Vol. 352, p. 959-960, 1998). Nonetheless, much still remains to be learned about the manner in which the complement system is involved in the progression of arteriosclerotic ischemic heart disease and its related diseases.